1. Field of the Invention
This invention relates to an electrical circuit tester and more particularly to such a device used for testing the correctness of the wiring of electrical household outlets or receptacles.
2. Description of the Prior Art
Various circuit testers have been developed for testing the correctness of the wiring of three-wire ground type electrical household outlets or receptacles. A number of these devices comprise three lamps connected between the prongs of a three-prong standard plug and disposed within a suitable housing. When such a circuit tester is plugged into the outlet being tested the combinations of energized lamps indicate whether or not the wiring of the outlet is correct. However, under certain conditions of incorrect receptacle wiring, differing voltages are impressed across the various lamps employed in such prior art circuit testers. In certain of the prior art testers, the lamps having lower voltages impressed thereacross will flicker or glow more dimly than the lamps having higher voltages impressed thereacross. It is possible therefore, that under differing conditions of receptacle wiring, all the lamps will light, but in differing degrees of brightness, depending upon the wired condition of the receptacle. In can be seen then that one using such a prior art circuit tester must not only determine which lamps are lit when the prior art tester is inserted in the receptacle but must also determine the brightness of each lamp relative to the brightness of each of the other lamps. If the user is relatively unskilled at making such determinations, the possibility of error in interpreting the indication given by the lamps is substantial. Moreover, should the receptacle being tested be located in an area of relatively high ambient light, the determination of the relative brightness of each of the lamps with respect to each of the other lamps may be difficult even for one relatively skilled.
By the present invention, the above problems associated with the prior art are avoided, and an approach is provided in which, with each of the wiring conditions tested for, various combinations of the indicating lamps glow brightly, the remainder of the lamps not glowing at all. Therefore, the problem of determining the relative brightness of each of the lamps and thereby risking a mistaken conslusion as to the wired condition of the receptacle being tested is obviated.
It is therefore an object of the present invention to provide an electric circuit tester employing indicating lamps which glow brightly in various combinations, the remainder of the lamps not glowing at all.